Wait.....
So, getting a refurbed Blu-Ray player for a higher price point than a brand new upscaling DVD player is "economical?"
And Top Gun looks better on Blu-Ray? I have to call BS on that. The Blu-Ray transfer was none too kind to this movie. They cropped the image for the transfer so a side-by-side comparison will be massively unfair - to Blu-Ray. The original was recorded on film, so the upscaling makes print artifacts more noticeable on the Blu-Ray versus the DVD. Unless you play the same tricks electronics retailers use (like turning the brightness way, way up on the Blu-Ray and way, way down on the standard def DVD), the DVD is not only going to have a comparable image, it actually looks better in many scenes, particularly the fighter jet sequences (where Blu-Ray should theoretically be better).
The only thing that "might" be better is that room shattering bass in the audio, and the Dolby 5.1 transfer they did for the DVD release is as good as it's going to get. You have to play funny audio games with the original source (read distort) to get any more bass out of it, and it doesn't sound any better (and noticeably worse for the transfer).
If you want to convince people to switch formats, go with the latest blockbusters with all the pretty visuals. Otherwise, the original wasn't recorded with enough fidelity to get a better image, and you may actually degrade the image if the film print is old enough (e.g. pre-digital recording). That and the dishonesty factor. The "improvement" you see for old movies on Blu-Ray is often simply the interlaced to progressive conversion that any old cheap $30 upscaling DVD player can achieve (that can still produce bad motion artifacting, no matter what digital format you use).